<?php
/**
 * Functions for dealing with OpenID trust roots
 *
 * PHP versions 4 and 5
 *
 * LICENSE: See the COPYING file included in this distribution.
 *
 * @package OpenID
 * @author JanRain, Inc. <openid@janrain.com>
 * @copyright 2005-2008 Janrain, Inc.
 * @license http://www.apache.org/licenses/LICENSE-2.0 Apache
 */

// Do not allow direct access
defined( '_JEXEC' ) or die( 'Restricted access' );

require_once 'Auth/OpenID/Discover.php';

/**
 * A regular expression that matches a domain ending in a top-level domains.
 * Used in checking trust roots for sanity.
 *
 * @access private
 */
define('Auth_OpenID___TLDs',
	   '/\.(ac|ad|ae|aero|af|ag|ai|al|am|an|ao|aq|ar|arpa|as|asia' .
	   '|at|au|aw|ax|az|ba|bb|bd|be|bf|bg|bh|bi|biz|bj|bm|bn|bo|br' .
	   '|bs|bt|bv|bw|by|bz|ca|cat|cc|cd|cf|cg|ch|ci|ck|cl|cm|cn|co' .
	   '|com|coop|cr|cu|cv|cx|cy|cz|de|dj|dk|dm|do|dz|ec|edu|ee|eg' .
	   '|er|es|et|eu|fi|fj|fk|fm|fo|fr|ga|gb|gd|ge|gf|gg|gh|gi|gl' .
	   '|gm|gn|gov|gp|gq|gr|gs|gt|gu|gw|gy|hk|hm|hn|hr|ht|hu|id|ie' .
	   '|il|im|in|info|int|io|iq|ir|is|it|je|jm|jo|jobs|jp|ke|kg|kh' .
	   '|ki|km|kn|kp|kr|kw|ky|kz|la|lb|lc|li|lk|lr|ls|lt|lu|lv|ly' .
	   '|ma|mc|md|me|mg|mh|mil|mk|ml|mm|mn|mo|mobi|mp|mq|mr|ms|mt' .
	   '|mu|museum|mv|mw|mx|my|mz|na|name|nc|ne|net|nf|ng|ni|nl|no' .
	   '|np|nr|nu|nz|om|org|pa|pe|pf|pg|ph|pk|pl|pm|pn|pr|pro|ps|pt' .
	   '|pw|py|qa|re|ro|rs|ru|rw|sa|sb|sc|sd|se|sg|sh|si|sj|sk|sl' .
	   '|sm|sn|so|sr|st|su|sv|sy|sz|tc|td|tel|tf|tg|th|tj|tk|tl|tm' .
	   '|tn|to|tp|tr|travel|tt|tv|tw|tz|ua|ug|uk|us|uy|uz|va|vc|ve' .
	   '|vg|vi|vn|vu|wf|ws|xn--0zwm56d|xn--11b5bs3a9aj6g' .
	   '|xn--80akhbyknj4f|xn--9t4b11yi5a|xn--deba0ad|xn--g6w251d' .
	   '|xn--hgbk6aj7f53bba|xn--hlcj6aya9esc7a|xn--jxalpdlp' .
	   '|xn--kgbechtv|xn--zckzah|ye|yt|yu|za|zm|zw)\.?$/');

define('Auth_OpenID___HostSegmentRe',
	   "/^(?:[-a-zA-Z0-9!$&'\\(\\)\\*+,;=._~]|%[a-zA-Z0-9]{2})*$/");

/**
 * A wrapper for trust-root related functions
 */
class Auth_OpenID_TrustRoot {
	/*
	 * Return a discovery URL for this realm.
	 *
	 * Return null if the realm could not be parsed or was not valid.
	 *
	 * @param return_to The relying party return URL of the OpenID
	 * authentication request
	 *
	 * @return The URL upon which relying party discovery should be
	 * run in order to verify the return_to URL
	 */
	function buildDiscoveryURL($realm)
	{
		$parsed = Auth_OpenID_TrustRoot::_parse($realm);

		if ($parsed === false) {
			return false;
		}

		if ($parsed['wildcard']) {
			// Use "www." in place of the star
			if ($parsed['host'][0] != '.') {
				return false;
			}

			$www_domain = 'www' . $parsed['host'];

			return sprintf('%s://%s%s', $parsed['scheme'],
						   $www_domain, $parsed['path']);
		} else {
			return $parsed['unparsed'];
		}
	}

	/**
	 * Parse a URL into its trust_root parts.
	 *
	 * @static
	 *
	 * @access private
	 *
	 * @param string $trust_root The url to parse
	 *
	 * @return mixed $parsed Either an associative array of trust root
	 * parts or false if parsing failed.
	 */
	function _parse($trust_root)
	{
		$trust_root = Auth_OpenID_urinorm($trust_root);
		if ($trust_root === null) {
			return false;
		}

		if (preg_match("/:\/\/[^:]+(:\d+){2,}(\/|$)/", $trust_root)) {
			return false;
		}

		$parts = @parse_url($trust_root);
		if ($parts === false) {
			return false;
		}

		$required_parts = array('scheme', 'host');
		$forbidden_parts = array('user', 'pass', 'fragment');
		$keys = array_keys($parts);
		if (array_intersect($keys, $required_parts) != $required_parts) {
			return false;
		}

		if (array_intersect($keys, $forbidden_parts) != array()) {
			return false;
		}

		if (!preg_match(Auth_OpenID___HostSegmentRe, $parts['host'])) {
			return false;
		}

		$scheme = strtolower($parts['scheme']);
		$allowed_schemes = array('http', 'https');
		if (!in_array($scheme, $allowed_schemes)) {
			return false;
		}
		$parts['scheme'] = $scheme;

		$host = strtolower($parts['host']);
		$hostparts = explode('*', $host);
		switch (count($hostparts)) {
		case 1:
			$parts['wildcard'] = false;
			break;
		case 2:
			if ($hostparts[0] ||
				($hostparts[1] && substr($hostparts[1], 0, 1) != '.')) {
				return false;
			}
			$host = $hostparts[1];
			$parts['wildcard'] = true;
			break;
		default:
			return false;
		}
		if (strpos($host, ':') !== false) {
			return false;
		}

		$parts['host'] = $host;

		if (isset($parts['path'])) {
			$path = strtolower($parts['path']);
			if (substr($path, 0, 1) != '/') {
				return false;
			}
		} else {
			$path = '/';
		}

		$parts['path'] = $path;
		if (!isset($parts['port'])) {
			$parts['port'] = false;
		}


		$parts['unparsed'] = $trust_root;

		return $parts;
	}

	/**
	 * Is this trust root sane?
	 *
	 * A trust root is sane if it is syntactically valid and it has a
	 * reasonable domain name. Specifically, the domain name must be
	 * more than one level below a standard TLD or more than two
	 * levels below a two-letter tld.
	 *
	 * For example, '*.com' is not a sane trust root, but '*.foo.com'
	 * is.  '*.co.uk' is not sane, but '*.bbc.co.uk' is.
	 *
	 * This check is not always correct, but it attempts to err on the
	 * side of marking sane trust roots insane instead of marking
	 * insane trust roots sane. For example, 'kink.fm' is marked as
	 * insane even though it "should" (for some meaning of should) be
	 * marked sane.
	 *
	 * This function should be used when creating OpenID servers to
	 * alert the users of the server when a consumer attempts to get
	 * the user to accept a suspicious trust root.
	 *
	 * @static
	 * @param string $trust_root The trust root to check
	 * @return bool $sanity Whether the trust root looks OK
	 */
	function isSane($trust_root)
	{
		$parts = Auth_OpenID_TrustRoot::_parse($trust_root);
		if ($parts === false) {
			return false;
		}

		// Localhost is a special case
		if ($parts['host'] == 'localhost') {
			return true;
		}
		
		$host_parts = explode('.', $parts['host']);
		if ($parts['wildcard']) {
			// Remove the empty string from the beginning of the array
			array_shift($host_parts);
		}

		if ($host_parts && !$host_parts[count($host_parts) - 1]) {
			array_pop($host_parts);
		}

		if (!$host_parts) {
			return false;
		}

		// Don't allow adjacent dots
		if (in_array('', $host_parts, true)) {
			return false;
		}

		// Get the top-level domain of the host. If it is not a valid TLD,
		// it's not sane.
		preg_match(Auth_OpenID___TLDs, $parts['host'], $matches);
		if (!$matches) {
			return false;
		}
		$tld = $matches[1];

		if (count($host_parts) == 1) {
			return false;
		}

		if ($parts['wildcard']) {
			// It's a 2-letter tld with a short second to last segment
			// so there needs to be more than two segments specified
			// (e.g. *.co.uk is insane)
			$second_level = $host_parts[count($host_parts) - 2];
			if (strlen($tld) == 2 && strlen($second_level) <= 3) {
				return count($host_parts) > 2;
			}
		}

		return true;
	}

	/**
	 * Does this URL match the given trust root?
	 *
	 * Return whether the URL falls under the given trust root. This
	 * does not check whether the trust root is sane. If the URL or
	 * trust root do not parse, this function will return false.
	 *
	 * @param string $trust_root The trust root to match against
	 *
	 * @param string $url The URL to check
	 *
	 * @return bool $matches Whether the URL matches against the
	 * trust root
	 */
	function match($trust_root, $url)
	{
		$trust_root_parsed = Auth_OpenID_TrustRoot::_parse($trust_root);
		$url_parsed = Auth_OpenID_TrustRoot::_parse($url);
		if (!$trust_root_parsed || !$url_parsed) {
			return false;
		}

		// Check hosts matching
		if ($url_parsed['wildcard']) {
			return false;
		}
		if ($trust_root_parsed['wildcard']) {
			$host_tail = $trust_root_parsed['host'];
			$host = $url_parsed['host'];
			if ($host_tail &&
				substr($host, -(strlen($host_tail))) != $host_tail &&
				substr($host_tail, 1) != $host) {
				return false;
			}
		} else {
			if ($trust_root_parsed['host'] != $url_parsed['host']) {
				return false;
			}
		}

		// Check path and query matching
		$base_path = $trust_root_parsed['path'];
		$path = $url_parsed['path'];
		if (!isset($trust_root_parsed['query'])) {
			if ($base_path != $path) {
				if (substr($path, 0, strlen($base_path)) != $base_path) {
					return false;
				}
				if (substr($base_path, strlen($base_path) - 1, 1) != '/' &&
					substr($path, strlen($base_path), 1) != '/') {
					return false;
				}
			}
		} else {
			$base_query = $trust_root_parsed['query'];
			$query = @$url_parsed['query'];
			$qplus = substr($query, 0, strlen($base_query) + 1);
			$bqplus = $base_query . '&';
			if ($base_path != $path ||
				($base_query != $query && $qplus != $bqplus)) {
				return false;
			}
		}

		// The port and scheme need to match exactly
		return ($trust_root_parsed['scheme'] == $url_parsed['scheme'] &&
				$url_parsed['port'] === $trust_root_parsed['port']);
	}
}

/*
 * If the endpoint is a relying party OpenID return_to endpoint,
 * return the endpoint URL. Otherwise, return None.
 *
 * This function is intended to be used as a filter for the Yadis
 * filtering interface.
 *
 * @see: C{L{openid.yadis.services}}
 * @see: C{L{openid.yadis.filters}}
 *
 * @param endpoint: An XRDS BasicServiceEndpoint, as returned by
 * performing Yadis dicovery.
 *
 * @returns: The endpoint URL or None if the endpoint is not a
 * relying party endpoint.
 */
function filter_extractReturnURL(&$endpoint)
{
	if ($endpoint->matchTypes(array(Auth_OpenID_RP_RETURN_TO_URL_TYPE))) {
		return $endpoint;
	} else {
		return null;
	}
}

function &Auth_OpenID_extractReturnURL(&$endpoint_list)
{
	$result = array();

	foreach ($endpoint_list as $endpoint) {
		if (filter_extractReturnURL($endpoint)) {
			$result[] = $endpoint;
		}
	}

	return $result;
}

/*
 * Is the return_to URL under one of the supplied allowed return_to
 * URLs?
 */
function Auth_OpenID_returnToMatches($allowed_return_to_urls, $return_to)
{
	foreach ($allowed_return_to_urls as $allowed_return_to) {
		// A return_to pattern works the same as a realm, except that
		// it's not allowed to use a wildcard. We'll model this by
		// parsing it as a realm, and not trying to match it if it has
		// a wildcard.

		$return_realm = Auth_OpenID_TrustRoot::_parse($allowed_return_to);
		if (// Parses as a trust root
			($return_realm !== false) &&
			// Does not have a wildcard
			(!$return_realm['wildcard']) &&
			// Matches the return_to that we passed in with it
			(Auth_OpenID_TrustRoot::match($allowed_return_to, $return_to))) {
			return true;
		}
	}

	// No URL in the list matched
	return false;
}

/*
 * Given a relying party discovery URL return a list of return_to
 * URLs.
 */
function Auth_OpenID_getAllowedReturnURLs($relying_party_url, &$fetcher,
			  $discover_function=null)
{
	if ($discover_function === null) {
		$discover_function = array('Auth_Yadis_Yadis', 'discover');
	}

	$xrds_parse_cb = array('Auth_OpenID_ServiceEndpoint', 'fromXRDS');

	list($rp_url_after_redirects, $endpoints) =
		Auth_Yadis_getServiceEndpoints($relying_party_url, $xrds_parse_cb,
									   $discover_function, $fetcher);

	if ($rp_url_after_redirects != $relying_party_url) {
		// Verification caused a redirect
		return false;
	}

	call_user_func_array($discover_function,
						 array($relying_party_url, $fetcher));

	$return_to_urls = array();
	$matching_endpoints = Auth_OpenID_extractReturnURL($endpoints);

	foreach ($matching_endpoints as $e) {
		$return_to_urls[] = $e->server_url;
	}

	return $return_to_urls;
}

/*
 * Verify that a return_to URL is valid for the given realm.
 *
 * This function builds a discovery URL, performs Yadis discovery on
 * it, makes sure that the URL does not redirect, parses out the
 * return_to URLs, and finally checks to see if the current return_to
 * URL matches the return_to.
 *
 * @return true if the return_to URL is valid for the realm
 */
function Auth_OpenID_verifyReturnTo($realm_str, $return_to, &$fetcher,
			  $_vrfy='Auth_OpenID_getAllowedReturnURLs')
{
	$disco_url = Auth_OpenID_TrustRoot::buildDiscoveryURL($realm_str);

	if ($disco_url === false) {
		return false;
	}

	$allowable_urls = call_user_func_array($_vrfy,
						   array($disco_url, &$fetcher));

	// The realm_str could not be parsed.
	if ($allowable_urls === false) {
		return false;
	}

	if (Auth_OpenID_returnToMatches($allowable_urls, $return_to)) {
		return true;
	} else {
		return false;
	}
}

?>